Konformationsabhängigkeit der Reaktivität N-vicinaler Methylengruppen in Polyamiden

During thermal oxidation of polyamides the N-vicinal methylene group is the preferred site of attack. According to spectroscopic data its reactivity should depend on its conformation to the amide group, as an interaction takes place between the π-electronic system of the carbonamide group and its C-H-bonds. By comparing the degradation products of thermally oxidized cyclo-bis-(?-aminocaproyl) with the N-vicinal methylene groups in a stable gauche-conformation, to polycaprolaotam, where a statistical distribution of gauche- and trans-conformations exists under the reaction conditions is shown that a N-vicinal methylene group in trans-conformation to the amide group is much more reactive than the same group in gauche-conformation. Investigations of the photooxidation of polys-caprolactam lead to the same result.     

Guest Editors' Introduction: Intelligent Transportation and Pervasive Computing

This special issue samples the developing area of pervasive computing in transportation systems through four feature articles and the Spotlight department, which consists of two interviews and two short articles. These contributions were written by automotive industry and academic experts and provide a diversity of views on a range of topics. Although the contributions focus on intelligent vehicular transportation, the technologies discussed also have applications in other transportation systems. This article is part of a special issue on Intelligent Transportation.     

Underwater sensor networks: applications, advances and challenges

This paper examines the main approaches and challenges in the design and implementation of underwater wireless sensor networks. We summarize key applications and the main phenomena related to acoustic propagation, and discuss how they affect the design and operation of communication systems and networking protocols at various layers. We also provide an overview of communications hardware, testbeds and simulation tools available to the research community.     

Combining spatial and colour information for content based image retrieval

Colour is one of the most important features in content based image retrieval. However, colour is rarely used as a feature that codes local spatial information, except for colour texture. This paper presents an approach to represent spatial colour distributions using local principal component analysis (PCA). The representation is based on image windows which are selected by two complementary data driven attentive mechanisms: a symmetry based saliency map and an edge and corner detector. The eigenvectors obtained from local PCA of the selected windows form colour patterns that capture both low and high spatial frequencies, so they are well suited for shape as well as texture representation. Projections of the windows selected from the image database to the local PCs serve as a compact representation for the search database. Queries are formulated by specifying windows within query images. System feedback makes both the search process and the results comprehensible for the user.     

Tumor necrosis factor-alpha, interleukin-1 beta, and interleukin-6 concentrations in cerebrospinal fluid predict ventriculoperitoneal shunt infection

OBJECTIVE: To determine the diagnostic value of cerebrospinal fluid tumor necrosis factor (TNF)-alpha, interleukin (IL)-1 beta, and IL-6 released into the cerebrospinal fluid of patients with ventriculoperitoneal shunt infection. DESIGN: Prospective, observational study. SETTING: University teaching hospital. PATIENTS: Sixty-four patients requiring cerebrospinal fluid aspiration for suspected ventriculoperitoneal shunt malfunction. INTERVENTIONS: Cerebrospinal fluid samples were obtained by shunt aspiration at the time of patient presentation. MEASUREMENTS AND MAIN RESULTS: TNF-alpha and IL-1 beta concentrations were measured by enzyme-linked immunosorbent assay, and IL-6 activity by bioassay. The sensitivity, specificity, predictive values, and overall efficiency for each cytokine were determined based on the cerebrospinal fluid culture results. Ten patients had positive cerebrospinal fluid cultures, eight of which yielded Staphylococcus species, and one each Acinetobacter and Pseudomonas. Cerebrospinal fluid TNF-alpha, IL-1 beta, IL-6, protein, and leukocyte concentrations were significantly increased in patients with shunt infection. Cerebrospinal fluid IL-6 activity had the highest diagnostic accuracy of the cytokines evaluated, with sensitivity of 80% and specificity of 98%. CONCLUSIONS: The presence of cerebrospinal fluid inflammatory cytokines strongly suggests ventriculoperitoneal shunt infection. Detection of these cytokines in the cerebrospinal fluid could be used for earlier diagnosis of bacterial infection.     

High speed and high resolution cardiac MRI (parallel acquisition techniques & modular imaging)

4. Conclusion In conclusion, further development is required before cardiac, and specifically coronary MRI, becomes a standard clinical tool, but new flexible concepts are being developed to achieve this goal.     

The long-range saliency of edge- and corner-based salient points.

A major goal of salient-point (SP) detection is increasing computational efficiency. Therefore, methods which can detect saliency of a large region by evaluation of only a small local patch are of particular interest. This paper checks for well-known detectors whether saliency outreaches the actual SPs.     

Endophthalmitis after radial keratotomy enhancement

A 45-year-old man developed endophthalmitis after a radial keratotomy (RK) enhancement. He developed severe intraocular inflammation, hypopyon, and dense vitreous membranes 4 days after the enhancement surgery. Cultures of the corneal wound yielded a heavy growth of Streptococcus viridans. The inflammation subsided after treatment with intraocular, intravenous, and topical antibiotics. The patient subsequently developed a cataract and retinal detachment. This case demonstrates the risk of endophthalmitis after RK enhancement.     

Optoelectronic generation of microwave power

In this letter a method of microwave generation by optoelectronic excitation of a charged resonator is presented. The basic principles of operation are explained and preliminary experimental results are discussed.